Fluid pressure systems often include manometric contactors adjusted in order to respond to different pressures in order to control the operation of devices such as pumps, electro-valves, alarm or safety devices, or to control the activation of braking control systems, for example, which are particularly found in motor vehicles.
In order to reduce the number of manometric contactors present in such systems, contactors have been produced which are capable of responding to several pressure values. French Pat. No. 2,300,408 describes such a contactor which, in particular, includes a sudden break contact equipment of "bistable" type whose trigger position does not correspond to the same displacement (and therefore pressure) values in both directions of displacement. The contactor described thus enables the regulation of the fluid pressure in a circuit between these two values by controlling the starting and stopping of a pump included in the circuit at each end of the differential pressure range thus defined.
Even though such a contactor can be satisfactory in certain applications, it should be noted that the accuracy of the pressure range limits that it defines depends strictly on the production quality of a bistable type spring, particularly of its cutting, its modulus of elasticity, etc. In other applications in which attempts are made to adjust accurately the pressure range limits, independently of each other, it may not be possible to achieve satisfaction with the capabilities of a contactor of the type described in the abovementioned patent.
There is known from the German Pat. No. DE-A-1,690,393 a double break electrical contactor including at least one contact bridge that is movable in translation and in rotation so that the two contacts of a same bridge close successively. This contactor, designed to improve the closing and braking capabilities of double break electrical devices, is not designed to provide the sequential closing of more than two pairs of contacts at separate times, as a function of three fluid pressure levels for example.
It is therefore an object of the present invention to provide an electrical contactor including at least three pairs of electrical contacts whose trigger conditions (from the open state to the closed state or vice versa), can be accurately adjusted according to a sequence determined by the development of a physical value such as a fluid pressure, for example.
It is also an object of the present invention to provide such a contactor associated with manometric means to control a pump acting on the pressure of a fluid in order to maintain this pressure within a predetermined range, by changing over the state of a pair of electrical contacts at each of the two limits of this range.
Another object of the present invention is to provide such a contactor, capable of controlling not only a fluid pump so that the pressure of the fluid is maintained within a predetermined range, but also signalling devices sensitive to the passing of the fluid pressure through a predetermined pressure value situated outside of this range, in order to then transmit an alarm signal.
These objects of the invention are achieved, together with others which will appear hereafter, with an electrical contactor of the type including a control member which moves in translation in order to pass through at least first, second and third positions each corresponding to the change of state of at least first, second, third and fourth pairs of electrical contacts which can be open or closed, first and second bars which carry first and second, and third and fourth electrical contacts respectively forming part of the first and second, and third and fourth pairs of contacts respectively, the control member working in conjunction with these bars in order to make each of them turn about an axis of rotation perpendicular to the axis of translation of the control member in such a way that at each of the ends of a rotational travel, each bar changes the state of one of the pairs of electrical contacts associated with this bar, this contactor being characterized in that the control member includes a monobloc part interposed between the two bars which are weighted towards each other and towards this part which includes at least two bearing surfaces each placed facing one of the bars in order to act on the latter and to make it swing through a rotational travel about an axis passing through a pair of contacts, the member being movable between these two bars in order to sequentially trigger the change of state of the four pairs of contacts, at the ends of the rotational travels of the bars, when it moves from one end to the other of its translational travel.
According to another feature of the invention, the position of the control member depends on the pressure of a fluid by means of a manometric component. The contactor according to the invention is then used to adjust the pressure of this fluid such that it remains within a predetermined pressure range, by an appropriate control of a pump for the pressurizing of this fluid.
The contactor also enables, in such an application, the control of the activation or deactivation of a device, such as a computer, associated with a fluid pressure system.